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package com.jgcomptech.tools.events;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Allows global event handler registration and forwards received
 * events to the appropriate registered event handlers.
 * @since 1.4.0
 */
public final class EventManager {
    private static EventManager instance;
    private final Map events = new HashMap<>();

    private EventManager() { }

    public static EventManager getInstance() {
        if(instance == null) instance = new EventManager();
        return instance;
    }

    private Event registerNewEvent(final String eventName,
                                   final EventTarget target) {
        if (eventName == null || eventName.isEmpty()) {
            throw new NullPointerException("Event name cannot be null!");
        }
        if (target == null) {
            throw new NullPointerException("Event target cannot be null!");
        }

        return events.put(eventName, new Event(target));
    }

    public  T registerNewEvent(final String eventName,
                                                final Class classRef,
                                                final EventType eventType)
            throws Exception {
        return registerNewEvent(eventName, classRef, new EventTarget<>(), eventType);
    }

    public  T registerNewEvent(final String eventName,
                                                final Class classRef,
                                                final EventType eventType,
                                                final List args)
            throws Exception {
        return registerNewEvent(eventName, classRef, new EventTarget<>(), eventType, args);
    }

    public  T registerNewEvent(final String eventName,
                                                final Class classRef,
                                                final EventTarget target,
                                                final EventType eventType)
            throws Exception {
        return registerNewEvent(eventName, classRef, target, eventType, new ArrayList<>());
    }

    public  T registerNewEvent(final String eventName,
                                                final Class classRef,
                                                final EventTarget target,
                                                final EventType eventType,
                                                final List args)
            throws IllegalAccessException, InvocationTargetException, InstantiationException, NoSuchMethodException {
        if (eventName == null || eventName.isEmpty()) {
            throw new IllegalArgumentException("Event name cannot be null!");
        }
        if (classRef == null) {
            throw new IllegalArgumentException("Event class ref cannot be null!");
        }
        if (target == null) {
            throw new IllegalArgumentException("Event target cannot be null!");
        }
        if (eventType == null) {
            throw new IllegalArgumentException("Event type cannot be null!");
        }
        if(args == null) {
            throw new IllegalArgumentException("Event Args cannot be null!");
        }

        Constructor constructor = classRef.getConstructor(EventTarget.class, EventType.class, List.class);

        T event = constructor.newInstance(target, eventType, args);

        events.put(eventName, event);

        return event;
    }

    public  T getEvent(final String eventName) { return (T) events.get(eventName); }

    /**
     * Fires the specified event with the specified source.
     * @param eventName the event to fire
     * @param source the event source which sent the event
     */
    public void fireEvent(final String eventName,
                          final Object source) {
        getEvent(eventName).fireEvent(source);
    }

    /**
     * Fires the specified event with the specified source and args.
     * @param eventName the event to fire
     * @param source the event source which sent the event
     * @param args a list of parameters to pass to the EventHandler
     */
    public void fireEvent(final String eventName,
                          final Object source,
                          final Object... args) {
        getEvent(eventName).fireEvent(source, args);
    }
}
 















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